diff --git a/bitbake/lib/bb/siggen.py b/bitbake/lib/bb/siggen.py
index 3a7dac4cb7..9485bf5d8a 100644
--- a/bitbake/lib/bb/siggen.py
+++ b/bitbake/lib/bb/siggen.py
@@ -30,6 +30,7 @@ class SignatureGenerator(object):
     name = "noop"
 
     def __init__(self, data):
+        self.basehash = {}
         self.taskhash = {}
         self.runtaskdeps = {}
         self.file_checksum_values = {}
@@ -61,11 +62,10 @@ class SignatureGenerator(object):
         return
 
     def get_taskdata(self):
-       return (self.runtaskdeps, self.taskhash, self.file_checksum_values, self.taints)
+        return (self.runtaskdeps, self.taskhash, self.file_checksum_values, self.taints, self.basehash)
 
     def set_taskdata(self, data):
-        self.runtaskdeps, self.taskhash, self.file_checksum_values, self.taints = data
-
+        self.runtaskdeps, self.taskhash, self.file_checksum_values, self.taints, self.basehash = data
 
 class SignatureGeneratorBasic(SignatureGenerator):
     """
@@ -133,7 +133,11 @@ class SignatureGeneratorBasic(SignatureGenerator):
                 var = lookupcache[dep]
                 if var is not None:
                     data = data + str(var)
-            self.basehash[fn + "." + task] = hashlib.md5(data.encode("utf-8")).hexdigest()
+            datahash = hashlib.md5(data.encode("utf-8")).hexdigest()
+            k = fn + "." + task
+            if k in self.basehash and self.basehash[k] != datahash:
+                bb.error("When reparsing %s, the basehash value changed from %s to %s. The metadata is not deterministic and this needs to be fixed." % (k, self.basehash[k], datahash))
+            self.basehash[k] = datahash
             taskdeps[task] = alldeps
 
         self.taskdeps[fn] = taskdeps
@@ -182,6 +186,7 @@ class SignatureGeneratorBasic(SignatureGenerator):
     def get_taskhash(self, fn, task, deps, dataCache):
         k = fn + "." + task
         data = dataCache.basetaskhash[k]
+        self.basehash[k] = data
         self.runtaskdeps[k] = []
         self.file_checksum_values[k] = []
         recipename = dataCache.pkg_fn[fn]